These teachings relate to relay spectrometers.
Current optically fast spectrometer designs are either too large in size for many applications, including but not limited to, unmanned aircraft, and forensic fieldwork, or their dispersing elements are complex and costly to fabricate, or they do not provide enough spatial and spectral imaging quality to meet the required system performance, or they do not provide enough throughput or optical speed, or they cannot provide a combination of these characteristics simultaneously.